1. Field of the Invention
The present invention pertains to electronic delay detonators and, in particular, to programmable electronic initiation delay detonators.
Electronic detonators are known for use in initiating explosive charges, e.g., for initiating booster charges used in mining and excavation applications. Such detonators are known for their precise delay characteristics relative to more traditional chemical-based delay units.
2. Related Art
U.S. Pat. No. 5,377,592 to Rode et al, dated Jan. 3, 1995, discloses an electronic digital delay unit powered by a pulse of energy generated by a piezoelectric transducer in response to an impulse-type initiation signal. The initiation signal stimulates the piezoelectric transducer to create a charge of electrical energy that is stored in a storage capacitor. Energy is drawn from the storage capacitor to run a timer circuit comprising an oscillator and a counter that counts oscillation pulses from the oscillator to a predetermined count. When the predetermined count is reached, a signal is generated to discharge the remaining energy from the storage capacitor to the electric igniter element, e.g., an exploding bridgewire. The detonator may be equipped with an externally accessible programming interface so that the timer circuit may be programmed with a delay after the detonator is constructed.
U.S. Pat. No. 5,435,248 to Rode et al, dated Jul. 25, 1995, discloses an electronic range digital delay detonator comprising fusible links that are used to perrnanently program a desired function delay into the detonator circuit.
Electronic detonators of the type described in aforesaid U.S. Pat. No. 5,435,248 and U.S. Pat. No. 5,377,592 comprise conventional oscillators and counters.